Prevalence of refractive errors among schoolchildren in Shiraz,Iran

Purpose: To determine the prevalence of refractive errors in Shiraz schoolchildren by age and gender. Methods: For this cross‐sectional study, random cluster sampling was carried out from students of the 2008–2009 academic year. After the initial interview, ophthalmic examinations including tests of visual acuity, non‐cycloplegic and cycloplegic refraction and binocular vision were performed. Myopia was defined as a spherical equivalent ≤?0.50 dioptre (D), hyperopia as ≥+2.0 D, and astigmatism as a cylinder refraction ≥0.75 D. All values for school grade and gender were directly standardized based on the total student population in the 2008–2009 school year. Results: A total of 2130 students were sampled, of which 1872 participated in the study (response rate = 87.88%). The prevalence of uncorrected, best‐corrected, presenting and spectacle corrected visual acuity of 6/12 or worse in the better eye was 6.46%, 0%, 1.49% and 0.9%, respectively. The prevalence rates of myopia, hyperopia and astigmatism were 4.35% (95% confidence interval [CI]: 2.89–5.82%), 5.04% (95% CI: 3.50–6.58%), and 11.27% (95% CI: 9.81–12.74%), respectively. Anisometropia was detected in 2.58% of schoolchildren. The prevalence of hyperopia significantly decreased with age (P = 0.021). Conclusions: Compared with other reported rates, the prevalence of myopia in the schoolchildren of Shiraz is similar to that in most places excluding East Asian countries, and that of hyperopia is in the mid range.     

Prevalence of habitual refractive errors and anisometropia among Dutch schoolchildren and hospital employees

Purpose: Refractive error (RE) is suggested to cause not only visual impairment, but also functional problems such as aspecific health complaints and lower levels of school achievement. During the last few decades the prevalence of myopia has increased worldwide, especially in Asia. We investigated the prevalence of habitual RE and anisometropia in a Dutch population of children and employees. Methods: In a cross‐sectional study, RE in both eyes of 520 children (aged 11–13 years) and 444 hospital employees (aged 17–60 years) were measured using an autorefractometer. The measurements were performed without using a cycloplegium. Pearson’s correlation coefficient (r) was used to analyse correlations between the right and left eyes. Chi‐square tests were used to test the differences between subgroups according to gender and age. Results: In schoolchildren 28% of right eyes were myopic (> 0.50 D) and 8% hyperopic (> 0.50 D). Pearson’s r between right and left eyes for spherical equivalent power (SEP) was 0.93. The mean cylinder deviation in right eyes was 0.26 D (range 0.00–4.50 D). Anisometropia > 1.00 D was present in 4.6% of children; 22% of children were not optimally (> 0.50 D) corrected. In hospital employees, 30% of right eyes were myopic (> 0.50 D) and 10% hyperopic (> 0.50 D). Pearson’s r between right and left eyes for SEP was 0.53. The mean cylinder deviation in right eyes was 0.35 D (range 0.00–5.75 D). Anisometropia > 1.00 D was present in 25% of employees. Anisometropia was more frequently present in employees aged 40–60 years, than in those aged 17–39 years (30% versus 18%; p = 0.02, Cramer’s V = 0.15). Conclusions: Refractive errors are common in children aged 11–13 years and in working adults aged 17–60 years. Distributions of sphere and cylinder deviations are similar for Dutch schoolchildren and hospital employees. Surprisingly, anisometropia proved to be more prevalent with age. In children many eyes are not optimally corrected. Increased attention should be paid to uncorrected and miscorrected REs.     

Relationship between habitual refractive errors and headache complaints in schoolchildren.

PURPOSE: Refractive error (RE) is considered to be a possible cause for headaches. We aimed to gain insight into the relation between habitual RE (sphere and astigmatism) and headache complaints. METHODS: In a cross-sectional study the habitual refractive state of 487 children, aged between 11 and 13 years, was measured using an autorefractometer (Topcon, RM-8000B). Headache complaints were measured using a questionnaire. Data were analyzed using Pearson correlation coefficients, bivariate analysis, and multiple logistic regression analysis. RESULTS: For right eyes we found 15% habitual myopia < -0.50 D and 12% habitual hyperopia > +0.50 D; habitual astigmatism > 0.25 D was found in 33% of children. Pearson R between right and left eyes was 0.76 for the spherical component and 0.42 for the cylindrical. In the total group of children 70% reported the occurrence of headache in the last year. These headaches were reported as "often or frequent" by 37% of children, "severe" by 15%, "with long duration" by 45%, and "with severe burden" by 27%. In the total sample we found various associations between gender, sphere/cylinder components of habitual RE, and headache complaints. Headache was reported more in girls than in boys. Of the total variance of headache complaints in girls, the sphere component of habitual RE explained 4% of frequency, 6% of intensity, 2% of duration, and 2% of amount of burden. Of the total variance of headache complaints in boys the cylinder component of habitual RE explained 3% of frequency, and 4% in amount of burden. CONCLUSION: Habitual RE and headache complaints are relatively common conditions in schoolchildren aged between 11 and 13 years. Headache complaints showed a small but statistically significant association with the sphere component of habitual RE in girls and the cylinder component of habitual RE in boys. The associations found between habitual RE and headache complaints indicate that habitual RE might be a risk factor for headache in children.     

Epidemiologic study of refractive errors in schoolchildren in socioeconomically deprived regions in Tunisia

PURPOSE: This study's purpose was to estimate the prevalence of common refractive errors in schoolchildren in low socioeconomic regions in Tunisia and to assess their effect on school performance. MATERIAL AND METHODS: This was a cross-sectional study done from November 1999 to January 2000 within the context of health care screening campaigns carried out by volunteer ophthalmologists and opticians in low-end socioeconomic regions in Tunisia. The concerned population was schoolchildren living in the cities of Tunis and Tabarka (North), Kerkena (Center), and Tozeur (South). We examined a total of 708 children with a mean age of 11.9 +/-3.21 years (from 6 to 20 years) and a sex ratio of 0.84. A cycloplegic refraction examination was performed on all the children. Statistical analyses with the chi squared test and the Fisher exact test allowed us to calculate the prevalence of the refractive errors totally and separately as well as the distribution according to age, sex, and region. We also searched for a possible relation between refractive errors and academic failure. RESULTS: Among the 708 children, 57.2% [CI(95)=53.4-60] had refractive errors, of which 31.6% [CI(95)=28.2-35.2] were hyperopic, whereas 9.1% [CI(95)=7.1-11.5] were myopic. Astigmatism was found in 16.4% [CI(95)=13.7-19.3]. The prevalence of myopia was significantly higher after the age of fourteen. It increased significantly with age (P=0.0003). The prevalence of hyperopia was significantly higher between the ages of 8 and 11 (P=0.0004). Hyperopic astigmatism was significantly more frequent between 6 and 9 years of age (P=0.001). There was no significant difference regarding sex. However, the distribution of the refractive errors by region showed a significantly high level of myopia in Tunis, Kerkena, and Tozeur. This difference disappeared with increasing age. The study of the effect of these refractive errors on school performance of these children from poor areas showed a significant association between all types of refractive errors and academic failure, with an odds ratio of 2.13 for all types of refractive errors, 2.69 for hyperopia, 2.87 for myopia, and 2.73 for astigmatism. CONCLUSION: This study showed the prevalence of refractive errors in a poor population of schoolchildren and emphasized the importance of such examinations. The ability of a child to participate in the educational experience is at least partially dependent on good vision.     

Prevalence of refractive errors among the school-going children in East Sikkim

Purpose:Vision plays an important role in child''s development for learning and communication. Uncorrected refractive error (URE) has become a major challenge to health care policy makers especially in school going children. We aim to report the prevalence of refractive error among the school students of the east district of Sikkim, India.Methods:A cross-sectional study was carried out among 15,954 school children under school health program of national program for control of blindness. The screening was conducted in 40 schools of east district which included primary, higher secondary, monastic and private schools.Results:The prevalence of refractive error was 6.7% among which myopia was the most common error present in 335 (31.1%) children, followed by astigmatism in 317 (29.4%) and the remaining 29 (2.6%) with hyperopia. The age group between 14-17 years had high prevalence of refractive error (9.2%). Females had slightly higher refractive error (6.93%) than males (5.9 %). Most backward classes were found to be highest suffering from refractive error (26.65%) and the least seen was found in schedule tribe (11.6%).Conclusion:The study provides a useful and baseline data about the refractive error amongst the school children of east Sikkim. A larger study needs to be conducted in all the schools of the state to get a clearer picture of RE and other eye related diseases to detect vision problem as early as possible.     

The prevalence of astigmatism in Taiwan schoolchildren.

PURPOSE: To understand the prevalence and distribution of astigmatism in schoolchildren in Taiwan, we analyzed and compared the nationwide survey data in 1995 and 2000. METHODS: A total of 11,175 students were enrolled in 1995, and 10,878 students were enrolled in 2000. The refractive status of each student was measured with an autorefractor during cycloplegia and rechecked with retinoscopy. RESULTS: About half of schoolchildren (57.5% in 1995 and 49.0% in 2000) had no astigmatism (<0.5 D). About one third of schoolchildren's astigmatism was <1 D (27.9% vs. 32.6%). Eleven percent of schoolchildren in 1995 and 13% in 2000 had astigmatism between 1.0 and 2.0 D. Less than 2% of students had astigmatism >3.0 D (1.3% in 1995 and 1.8% in 2000). Most astigmatism was with-the-rule: 83.3% in 1995 and 89.9% in 2000. Only 16.6% of children in 1995 and 9.7% in 2000 had against-the-rule astigmatism. Very little astigmatism was oblique (0.1% in 1995 and 0.4% in 2000). The rate of myopic astigmatism increased with age. In contrast, the rate of hyperopic and mixed astigmatism decreased with age. In addition, the rate of with-the-rule astigmatism increased and the rate of against-the-rule decreased with respect to age, but oblique astigmatism was rather stable with age. CONCLUSIONS: Most schoolchildren had little or no astigmatism. In Taiwan, most astigmatism is <1 D and is myopic with-the-rule astigmatism. There was more myopic astigmatism and with-the-rule astigmatism in 2000 than in 1995.     

Prevalence of visual impairment and estimation of refractive errors among school children in Kakamega, Kenya

AIM: To investigate the prevalence of visual impairment (VI) and provide an estimation of uncorrected refractive errors in school-aged children, conducted by optometry students as a community service. METHODS: The study was cross-sectional. Totally 3343 participants were included in the study. The initial examination involved assessing the uncorrected distance visual acuity (UDVA) and visual acuity (VA) while using a +2.00 D lens. The inclusion criteria for a subsequent comprehensive cycloplegic eye examination, performed by an optometrist, were as follows: a UDVA<0.6 decimal (0.20 logMAR) and/or a VA with +2.00 D ≥0.8 decimal (0.96 logMAR). RESULTS: The sample had a mean age of 10.92±2.13y (range 4 to 17y), and 51.3% of the children were female (n=1715). The majority of the children (89.7%) fell within the age range of 8 to 14y. Among the ethnic groups, the highest representation was from the Luhya group (60.6%) followed by Luo (20.4%). Mean logMAR UDVA choosing the best eye for each student was 0.29±0.17 (range 1.70 to 0.22). Out of the total, 246 participants (7.4%) had a full eye examination. The estimated prevalence of myopia (defined as spherical equivalent ≤-0.5 D) was found to be 1.45% of the total sample. While around 0.18% of the total sample had hyperopia value exceeding +1.75 D. Refractive astigmatism (cil<-0.75 D) was found in 0.21% (7/3343) of the children. The VI prevalence was 1.26% of the total sample. Among our cases of VI, 76.2% could be attributed to uncorrected refractive error. Amblyopia was detected in 0.66% (22/3343) of the screened children. There was no statistically significant correlation observed between age or gender and refractive values. CONCLUSION: The primary cause of VI is determined to be uncorrected refractive errors, with myopia being the most prevalent refractive error observed. These findings underscore the significance of early identification and correction of refractive errors in school-aged children as a means to alleviate the impact of VI.     

The role of light in pathogenesis of refractive errors

PURPOSE: To present and account the results of newest experimental and clinical investigations on the subject of the light effect on the creation of refractive errors. MATERIAL AND METHODS: A review of literature concerning the role of the light in the refractive errors' pathogenesis has been performed. RESULTS: The influence of continuous light and night adaptation on the eyeball development as well as on the creation of refractive errors in experimental conditions are discussed. The anatomical and biochemical changes taking place in the course of experimental myopia are described. The entities of diseases predisposing to the creation of myopia are characterized. The results of the newest clinical investigations in which was shown that myopia and hyperopia might be associated with sleeping in lighted rooms up to the age of two are presented as well as accounted. CONCLUSIONS: Light and darkness play an important role in the proper eye development. Disturbance of the diurnal cycle over the time during which refraction forms may create refractive errors.     

Prevalence rates of refractive errors in Sumatra,Indonesia

PURPOSE: To determine the prevalence rates of myopia, hyperopia, astigmatism, and anisometropia in a prevalence survey of adults in Sumatra, Indonesia. METHODS: A population-based prevalence survey of 1043 adults 21 or more years of age was conducted in five rural villages and one provincial town of the Riau Province, Sumatra, Indonesia. A one-stage household cluster sampling procedure was used wherein 100 households were selected from each village or town. Refractive error measurements were obtained with one of two handheld autorefractors. Household interviews were conducted to obtain information on relevant lifestyle risk factors. RESULTS: The age-adjusted overall prevalence rates of myopia (SE [spherical equivalent] at least -1.0 D), hyperopia (SE of at least +1.0 D), astigmatism (cylinder of at least -1.0 D), and anisometropia (SE difference of +1.0 D) were 26.1% (95% confidence interval [CI]: 23.4-28.8), 9.2% (95% CI: 7.4-11.0), 18.5% (95% CI: 16.2-20.8), and 15.1% (95% CI: 12.9-17.4), respectively. The age-adjusted overall prevalence rate of high myopia (SE at least -6.0 D) was 0.8% (95% CI: 0.2-1.5). In a multiple logistic regression model, myopia rates varied with age and increased with income. Hyperopia, astigmatism, and anisometropia rates were independently higher in older adults. CONCLUSIONS: The prevalence rates of myopia in provincial Sumatra are higher than the rates in white populations, but lower than the rates in other urbanized Asian countries such as Singapore. The prevalence rate of high myopia is lower than in most other populations, and other refractive errors are common.